Conventionally, radio device, for example, a milliwave radar mounted on a vehicle uses electromagnetic waves of a milliwave band, and detects a distance and a relative speed between the vehicle and a vehicle running in front to be applied to achieve a cruise control and a safety measure to reduce damage on a driver when a collision cannot be avoided. In many cases, such an in-vehicle milliwave radar multiplies 1/N (where N is a positive integer of 2 or larger) of a frequency to obtain a high-frequency transmission signal of a milliwave band. In this case, many frequency components are present in a module. Therefore, it is very difficult to satisfy a desired electromagnetic interference (EMI) characteristic.
In the in-vehicle milliwave radar, a transmission/reception module usually includes a high-frequency package including a high-frequency semiconductor for a radar device, a control/interface substrate that applies a bias signal and a control signal to the high-frequency package, and a waveguide. To satisfy the EMI characteristic, conventionally, a whole body of the transmission/reception module is configured to be covered with a metallic cover.
However, when such a configuration that the transmission/reception module is covered with the metallic cover is applied, an expensive casing and the like are necessary. Therefore, to reduce manufacturing cost, it is necessary to take measures within the high-frequency package.
According to patent literature 1, an integrated circuit part for a high-frequency signal and a dielectric substrate are mounted on a metallic base member, with a micro slip line formed on the dielectric substrate. These parts are covered with a metallic frame member and a metallic lid member. To the integrated circuit part for a high-frequency signal mounted on the base, a bias is applied via a bias terminal.
Patent Literature 1: Japanese Patent Application Laid-Open No. 2000-31812